Indoor Air Quality + Performance

I. Indoor Air Quality - Introduction

Studies have shown that volatile organic compounds (VOCs), carbon dioxide (CO2), and human bioeffluents are common harmful pollutants that effect human productivity and are often found at high levels indoors (Satish 2012, Allen 2016, Zhang 2017). Reducing these indoor air contaminants with by providing adequate levels of outdoor air through improved ventilation has been shown to increase mental cognition and productivity in offices (Clements-Croome 2008, Wyon 2004, Allen 2016, Satish 20120 and schools (Fisk 2017) in several academic studies.

II. Impact

Studies have shown that volatile organic compounds (VOCs), carbon dioxide (CO2), and human bioeffluents are common harmful pollutants that effect human productivity and are often found at high levels indoors (Satish 2012, Allen 2016, Zhang 2017). Reducing these indoor air contaminants with by providing adequate levels of outdoor air through improved ventilation has been shown to increase mental cognition and productivity in offices (Clements-Croome 2008, Wyon 2004, Allen 2016, Satish 2012) and schools (Fisk 2017) in several academic studies.

III. Productivity in Offices

Cognitive function is a driver of real-world productivity in office workers (Allen et al. 2016), furthermore, it encompasses the quality of real-time decision-making and problem-solving (Azuma et al. 2018). Standards for ventilation have been largely based on human comfort with indicators such as bioeffluents, body odor, and satisfaction (ASTM-D6245). More recent research shows that other indicators like CO2 have an influence on human performance at thresholds lower than those that were developed as acceptable standards based on human comfort (Allen 2016).

Low ventilation rates are associated with low cognitive performance and are indicated by the presence of pollutants such as CO2 (Maddalena et al. 2015). A study by Seppanen et al. found that work performance, indicated by speed and accuracy of typical office tasks, increased at a rate of 0.8% with every 10 cfm/person increase in ventilation between 14 to 30 cfm/person, but the benefit of increased ventilation was not as great over 30 cfm/person (Seppanen 2005).

Another study by Allen et al. comparing cognitive performance of office workers in variously ventilated spaces similarly found that increased outdoor ventilation, lower CO2 concentrations, and lower total volatile organic compounds (TVOCs) concentrations improves indoor air quality and significantly improves productivity. Overall, a 21% decrease in typical participant cognitive score across nine cognitive function domains was seen with 400 ppm increases in CO2 concentrations, and an 18% increase in scores was associated with a 20-cfm increase in outdoor air per person (Allen 2016). The study used a validated, computer-based cognitive test to assess office worker performance. CO2 concentration had a major impact on cognitive function scores (Allen 2016). To contextualize this study, background outdoor CO2 concentrations are typically 350-400 ppm (ESRL 2020). ASHRAE Standard 62.1 suggests an airflow rate of 20 cfm/person, which corresponds to a CO2 concentration of 945 ppm, commonly stated as 1,000 ppm (ASTM-D6245). This standard is commonly required by local building codes that use ASHRAE standards (Allen 2016). In Allen’s study, changes in CO2 concentrations from 550 ppm to 945 resulted in a 15% reduction in cognitive test scores. Changes in concentrations from 550 to 1400 ppm, resulted in 50% decreases in cognitive scores. (Allen 2016). An earlier study by Satish et al. found similar effects of CO2 concentrations on decision-making performance using the same computer-based test. In this study, scores in seven of nine cognitive function domains decreased by 11-23% when the CO2 concentration increased from 600ppm to 1,000ppm (Satish 2012).

Researchers have found that CO2 by itself does not cause any health or behavior impacts. Rather, it is an indicator of low outdoor air ventilation rates and thus increased presence of additional pollutants such as TVOCs and the production of human bioeffluents, which have a negative impact on cognitive performance (Zhang et al. 2016; Zhang et al. 2017; Maula et al. 2017).

The health and performance impacts of increased CO2 concentration is shown in the table below, and is based on information from multiple sources (Table 1).

The cognitive function tests by Allen et al. also provided evidence of impacts on decision-making performance due to TVOC concentrations. Keeping other variables constant, on average, scores in the various cognitive function domains were 60% higher in building conditions with low TVOCs around 50μg/m3 as compared to office environments with high TVOCs around 550μg/m3 (Allen 2016).

IV. Productivity in Schools

In the United States, indoor carbon dioxide concentrations tend to be much higher in school classrooms than in office buildings. Low ventilation rates with high CO2 concentration are widely found in many mechanically ventilated schools, and increasing ventilation rates impose energy cost and increased size of HVAC systems. (Fisk 2017). Findings on the impact of CO2 concentrations above 600 ppm on cognitive functions (Allen 2016, Satish 2012) are particularly concerning since many spaces far exceed the 1,000ppm standard. For example, 66% of 120 classrooms in Texas (Corsi et al. 2002) and 45% of 435 classrooms in Washington and Idaho (Shendell et al. 2004) were found to be above this 1,000ppm threshold, it was reported that elevated CO2 concentrations were associated with an increase in student absences (Shendell et al. 2004). Another study found that a 17% increase of CO2 concentration lead to a 16% reduction in performance, as measured by math and code tests (Dorizas 2015). Fisk’s research shows that students perform better academically in classrooms with higher ventilation rates, which are associated with lower levels of CO2 (Fisk 2017). Teachers, students, and school staff can by negatively affected by poor indoor air quality leading to common associated health problems like coughs, eye irritation, headaches, allergic reactions, aggravate asthma or other respiratory illnesses (EPA). According to the Asthma and Allergy Foundation of America, nearly 1 in 12 school-aged children has asthma, which is the leading cause of school absenteeism due to chronic illness (AAFA, EPA).

V. Reduced Absenteeism

Enhanced ventilation in buildings can improve performance of workers by 8% by reducing absenteeism and improving health overall (MacNaughton 2015). Healthier buildings reduce sick time and increase productivity (Miller 2009). Effective ventilation and the absence of volatile organic compounds leads to happier, healthier workers. Additional information regarding absenteeism due to the adverse health implications of indoor air quality can be found in the IAQ Physiological Health Research Brief.

VI. References

Review Articles

• Clements-Croome, Derek J. “Work performance, productivity and indoor air.” Scandinavian Journal of Work Environment & Health Supplement (2008): 69-78.
• Fisk, William J. “The ventilation problem in schools: literature review.” Indoor Air 27, no. 6 (2017): 1039-1051.
• Gerardi, Daniel A. “Building-related illness.” Clinical Pulmonary Medicine 17, no. 6 (2010): 276-281.
• Miller, Norm, Dave Pogue, Quiana Gough, and Susan Davis. “Green buildings and productivity.” Journal of Sustainable Real Estate 1, no. 1 (2009): 65-89.
• Seppanen, Olli, William J. Fisk, and Q. H. Lei. “Ventilation and Work Performance in Office Work.” (2005).
• Wallingford, K. M. “NIOSH Indoor Air Quality Investigations in Non-industrial Workplaces: An Update.” Internal NIOSH report. (1986).

Primary Research

• Allen, Joseph G., Piers MacNaughton, Usha Satish, Suresh Santanam, Jose Vallarino, and John D. Spengler. “Associations of cognitive function scores with carbon dioxide, ventilation, and volatile organic compound exposures in office workers: a controlled exposure study of green and conventional office environments.” Environmental health perspectives 124, no. 6 (2016): 805-812.
• Corsi, R. L., V. M. Torres, M. Sanders, and K. A. Kinney. “Carbon dioxide levels and dynamics in elementary schools: results of the TESIAS Study.” Indoor Air 2 (2002): 74-79.
• Dorizas, Paraskevi Vivian, Margarita-Niki Assimakopoulos, and Mattheos Santamouris. “A holistic approach for the assessment of the indoor environmental quality, student productivity, and energy consumption in primary schools.” Environmental monitoring and assessment 187, no. 5 (2015): 259.
• Kajtár, László, and Levente Herczeg. “Influence of carbon-dioxide concentration on human well-being and intensity of mental work.” QJ Hung. Meteorol. Serv 116 (2012): 145-169.
• MacNaughton, Piers, James Pegues, Usha Satish, Suresh Santanam, John Spengler, and Joseph Allen. “Economic, environmental and health implications of enhanced ventilation in office buildings.” International journal of environmental research and public health 12, no. 11 (2015): 14709-14722.
• Maula, H., V. Hongisto, V. Naatula, A. Haapakangas, and H. Koskela. “The effect of low ventilation rate with elevated bioeffluent concentration on work performance, perceived indoor air quality, and health symptoms.” Indoor Air 27, no. 6 (2017): 1141-1153.
• Satish, Usha, Mark J. Mendell, Krishnamurthy Shekhar, Toshifumi Hotchi, Douglas Sullivan, Siegfried Streufert, and William J. Fisk. “Is CO2 an indoor pollutant? Direct effects of low-to-moderate CO2 concentrations on human decision-making performance.” Environmental health perspectives 120, no. 12 (2012): 1671-1677.
• Shendell, Derek G., William J. Fisk, Michael G. Apte, and David Faulkner. “Associations between classroom CO2 concentrations and student attendance in Washington and Idaho.” (2012).
• Vehviläinen, Tommi, Harri Lindholm, Hannu Rintamäki, Rauno Pääkkönen, Ari Hirvonen, Olli Niemi, and Juha Vinha. “High indoor CO2 concentrations in an office environment increases the transcutaneous CO2 level and sleepiness during cognitive e work.” Journal of occupational and environmental hygiene 13, no. 1 (2016): 19-29.
• Wyon, David P. “The effects of indoor air quality on performance and productivity.” Indoor air 14, no. 1 (2004): 92-101.
• Zhang, Xiaojing, Pawel Wargocki, and Zhiwei Lian. “Human responses to carbon dioxide, a follow-up study at recommended exposure limits in non-industrial environments.” Building and Environment 100 (2016): 162-171.
• Zhang, Xiaojing, Pawel Wargocki, Zhiwei Lian, and Camilla Thyregod. “Effects of exposure to carbon dioxide and bioeffluents on perceived air quality, self‐assessed acute health symptoms, and cognitive performance.” Indoor air 27, no. 1 (2017): 47-64.

Other

• AAFA (Asthma and Allergy Foundation of America). “Asthma Facts and Figures.” Asthma and Allergy Foundation of America. https://www.aafa.org/asthma-facts (2020).
• ANSI/ASHRAE 62.-2019. “Ventilation for Acceptable Indoor Air Quality.” American Society of Heating Refrigerating and Air-Conditioning Engineers. https://ashrae.iwrapper.com/ViewOnline/Standard_62.1-2019 (2020).
• ASTM-D6245. “Standard Guide for Using Indoor Carbon Dioxide Concentrations to Evaluate Indoor Air Quality and Ventilation.” Compass ASTM (2018).
• EPA (Environmental Protection Agency). “Report on the Environment – Indoor Air Quality.” Environmental Protection Agency. https://www.epa.gov/report-environment/indoor-air-quality (2020).
• ESRL (Earth System Research Laboratories). National Oceanic and Atmospheric Administration https://www.esrl.noaa.gov/ (2020).
• WDHS (Wisconsin Department of Health Services). “Carbon Dioxide.” Wisconsin Department of Health Services. https://www.dhs.wisconsin.gov/chemical/carbondioxide.htm (2020).